A seedless grape has considerable advantages in wine-making in that the wine being produced can be left on the skins for longer than in the case of conventional ‘Chardonnay’ clones, without developing the bitter taste associated with seeds.
The improved grape of the present invention was first noticed, in January of 1999, by one of the inventors, who observed a vine having unusually small bunches with small berries in a ‘Chardonnay I10V1’ planting on the property/vineyard in Paringa, South Australia, Australia. On closer inspection, the ‘Chardonnay I10V1’ grapes were also found to be seedless.
A year later, a viticultural consultant suggested that the vine should be investigated, as it might be of value in winemaking. A test sample of two liters of wine was produced from the grapes. The wine showed potential, despite receiving insufficient attention during the winemaking process.
In the next year's vintage (2001), further tests were conducted. The grapes were found to contain 12 g/l total acid at 13.9 Be, which was a remarkable result. The grapes were made into wine in the laboratory, and this time the wine appeared very promising. The wine analysis was 8.0 g/l total acid, pH was 2.85 (remarkably good), and the alcohol content was 13.9%.
The mother vine of the seedless ‘Chardonnay I10V1’ plant was DNA typed using six microsatellite loci, and found to match the genotype of material designated as ‘Chardonnay I10V1’, as recorded in the databases. The seedless clone of ‘Chardonnay I10V1’ was designated ‘Chardonnay I10V1-S.’
During the dormancy period of 2001, the ‘Chardonnay I10V1-S’ mother vine was tested and no vitiviruses or phytoplasmas were detected.
In spring of 2001, sufficient vines were propagated from the ‘Chardonnay I10V1-S’ mother vine to plant two 100-meter-long rows on Paulsen rootstock, and one row on their own roots on the property/vineyard in Paringa, South Australia, Australia (CT 5136/331 Hundred Murtho Section 66). These new vines were regularly examined, through to harvest 2004, for any variation from the mother vine. Three vines each produced an individual cane (shoot) that reverted back to the original ‘Chardonnay I10V1’. These canes had normal sized berries and bunches and had normal leaves. This reversion rate is within normally accepted tolerances. All the other canes produced on the three vines remained seedless, as did all the canes on the other 190 vines.
Meanwhile, in late 2002, further trials were carried out with a planting of the ‘Chardonnay I10V1-S’ on a property on Nixon Road, Monash, South Australia, Australia. The trial planting was covered by a non propagation agreement.
During vintage 2003, wine was produced from the mother vine and its young progeny. The yield from the mother vine was 31 kg (equivalent to 38.5 t/ha), and winemakers examining the wine produced from the seedless grapes were favourably impressed.
During the 2004 vintage, wine was again produced from the mother and daughter seedless vines, with similar results.